1. Field of the Invention
The present invention relates to a refrigeration cycle apparatus, having a liquid receiver for separating gas and liquid in the refrigerant which has passed through a refrigerant condenser to accumulate the liquid refrigerant, the refrigeration cycle apparatus having an improved refrigerant filling characteristic in the refrigeration cycle and preferably being used for a air conditioner for a vehicle.
2. Description of the Related Art
The applicant has proposed, in the Japanese Unexamined Patent Publication No. 2000-74527, a refrigeration cycle apparatus which allows the refrigerant, which has passed through a refrigerant condenser and has been condensed, to flow into a liquid receiver from upper and lower paths.
According to this refrigeration cycle apparatus, due to the cooling effect of the liquid refrigerant flowing into the upper space in the liquid receiver, the refrigerant in the upper space in the liquid receiver is not gasified by the heat from the outside. For this reason, the space in the liquid receiver may be used effectively for accumulating the liquid refrigerant up to the upper space.
The inventors have learned, specifically when investigating and evaluating the above prior art, that the refrigerant filling characteristic widely fluctuates according to the flow rate of the refrigerant flowing into the liquid receiver from the upper part thereof.
It is therefore an object of the present invention to provide a refrigeration cycle apparatus having an improved refrigerant filling characteristic, wherein preventing heat damage due to the heat given to the liquid receiver from the outside and securing a good bubble disappearing characteristic in the liquid refrigerant flowing out from the liquid receiver may be mutually compatible because the flow rate of the refrigerant flowing into the liquid receiver from the upper part thereof is specifically set at a suitable value.
In order to achieve the above object, the present invention provides a refrigerant cycle apparatus comprising an upper refrigerant flow-in means (32) allowing the refrigerant which has passed through a condenser (2) to flow into the upper part of a liquid receiver (31) and a lower refrigerant flow-in means (33, 330) allowing the refrigerant which has passed through the condenser (2) to flow into the lower part of the liquid receiver (31), wherein the flow rate (Gr1) of refrigerant flowing into the upper part of the liquid receiver (31) from the upper refrigerant flow-in means (32) is set at a value between 30 kg/h and 110 kg/h.
It has become apparent from analysis of an experiment by the inventors that the wall around the upper space of the liquid receiver (31) is effectively cooled by the refrigerant flowing into the liquid receiver (31) from the upper part thereof when the flow rate (Gr1) of refrigerant flowing into the upper part of the liquid receiver (31) from the upper refrigerant flow-in means (32) is set at 30 kg/h or more. For this reason, it is clear that gasifying of the refrigerant in the liquid receiver (31) may be restricted effectively even under the condition that heat is given to the liquid receiver (31) from the outside (for example, when the hot air which has passed through the condenser and radiator turns to the front of the condenser at engine idling), and thereby the space in the liquid receiver (31) may be effectively used to accumulate the liquid refrigerant.
As a result, an xe2x80x9coverfilling cycle conditionxe2x80x9d which happens when the refrigerant to be originally accumulated in the liquid receiver (31) overflows to the condenser (2), may be restricted and, thereby, an undesired state such as increase of compressor power (decrease of COP (Coefficient of Performance)) resulted from the overfilling cycle condition may be prevented.
Furthermore, it has become apparent from an analysis of experiments by the inventors that instability in the level of the liquid refrigerant in the liquid receiver (31), resulting from the dynamic pressure which arises when the refrigerant flows into the liquid receiver (31) from the upper side thereof, may be restricted by limiting the flow rate (Gr1) of the refrigerant flowing into the upper part of the liquid receiver (31) from the upper refrigerant flow-in means (32) to 110 kg/h or less, and thereby mixing of the gas refrigerant into the liquid refrigerant which flows out from the liquid receiver (31) may be restricted. In result, the good bubble disappearing characteristic of the liquid refrigerant may be secured, and thereby the refrigerant filling characteristic may be improved.